Catheter-needle



April 4, 1970 M. L. HENKlN 3,506,007

CATHETER-NEEDLE Filed July 24. 196'? 2 Sheets-Sheet 1 MEL vy/v L.HA/M/M,

(5y M5 firropmgys JMvEA/r'aa April 14, 1970 M. L. HENKIN 3,506,007

CATHETER-NEEDLE Filed July 24. 1967 2 Sheets-Sheet 2 United StatesPatent 3,506,007 CATHETER-NEEDLE Melvyn L. Henkin, 3326 Sawtelle Blvd.,Los Angeles, Calif. 90066 Filed July 24, 1967. Ser. No. 655,513 Int. Cl.A61m 5/00 US. Cl. 128-221 Claims ABSTRACT OF THE DISCLOSURE An improvedcatheter-needle for injecting and withdrawing fluids from cavities andchannels of a subject is disclosed consisting of a hollow needle; acatheter disposed exteriorly of the needle and slidable thereon; and, areleasably interlocking hub assembly interconnecting the needle and thecatheter. The interlocking hub assembly is constructed to selectivelymaintain the needle in a predetermined withdrawn position within thecatheter. Alternative catheter constructions are disclosed whereby thecatheter may be selectively maintained in a predetermined insertedposition.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates generally to an instrument for the administration of fluids intothe cavities and channels of a human body and more particularly to animproved epidural catheter-needle for the introduction and placement ofa catheter and the administration of epidural anesthesia.

' Description of the prior art The use of hollow needles and flexiblecatheters ,in the administration off epidural anesthesia is not new.However, the heretofore utilized cooperation of catheter and needle isfound to have severe disadvantages in the light of the presentinvention.

In known epidural administrations, a hollow needle is introduced intothe spinal structure through the interspinous ligaments and thebordering ligamenturn flavurn directly into the epidural space. As theepidural space is only approximately two to four millimeters in depth,the cutting edge of the needle is thereby laced in critical proximity tothe dura, the outer membrane of the cerebrospinal fluid canal.Accidental penetration of the dura in administration of the anestheticagent into the canal could cause severe damage to the patient. In thisposition, the needle itself is used for administration of test orinitial dosages of the anesthetic agent and as an external guide for thethreading therewithin of a long, extremely fine catheter utilized forrepeated and/or continuous administration of the anesthetic agent. Afterplacement of the fine catheter, the hollow needle must be carefullywithdrawn from the subject avoiding dislodgment of the fine catheter. g

A major disadvantage of previously known epidural administrationtechniques is the difficult manufacture of a needle suitable to bothminimizing the possibility of dura penetration and guiding the finecatheter in the desired direction within the epidural space. To datethere does not exist a needle which satisfactorily achieves theseobjectives or that can be manufactured at a cost compatible withdisposable use. A few blunt-needle configurations have been found tosubstantially preclude dura penetration. However, introduction of thelarge bore blunt needle through the interspinous ligaments andligamentum fiavum is extremely laborious, requiring great force.Furthermore, a blunt needle must have its opening at or near a rightangle to its axis. Therefore, the internally threaded catheter mustnegotiate a sharp turn in order to emerge into the epidural space. Greatdiificulty in catheter threading therewithin has been experienced; suchditficulty sometimes resulting in complete failure of the technique.

Another disadvantage of the known administration techniques is that thecatheter used must be extremely fine, as it must be threaded through theneedle, thus rendering aspiration relatively unreliable. The small sizeand mode of placement of the catheter increases the likelihood of itsundetected erosion into either a blood vessel or the subarachnoid space.Further, injection of the anesthetic agent through the extremely finecatheter, often requires undesirably great pressures because of the highresistance to fluid flow imposed by the relatively small bore of thecatheter over its entire length. Such inherent difiiculty of fluid flowis further compounded by the known tendency of the fine catheter totwist and kink within the epidural space thereby further restrictingfluid flow. A larger bore catheter, as provided by the presentinvention, substantially eliminates such undesirable restrictions tofluid flow.

The problems attendant on the internally threaded catheter have beenalleviated to some extent in general intravenous and intravascularapplications. That art discloses the use of a larger bore catheterexternally slidable on a hollow needle. In that application, the needleand catheter are longitudinally introduced into the vein or vessel. Theneedle is then Withdrawn into the catheter a small amount and thecombination further advanced. When the catheter is firmly lodged withinthe channel, the needle is withdrawn from within the catheter leavingthe large bore catheter in the vein or vessel. Such an application,however, is neither completely satisfactory nor does it fully meet themajor problem attendant on epidural introductions. A major disadvantageof such placements of exteriorly disposed catheters is the awkwardnessand relative lack of precision of hand holding the combination with theneedle tip sheathed within the catheter. There exists the ever-presentdanger of the needle tip becoming unsheathed during advancement of thecombination thereby damaging the vessel and necessitating withdrawal andreinsertion in another vessel. Further, with respect to epiduralapplications, the nature of the spinal structure precludes alongitudinal needle entry into the epidural space; the needle entry pathbeing more transverse to the epidural space. Consequently, consideringthe narrowness of the epidural space, a transverse insertion of anexteriorly disposed catheter-needle as presently known does not allowselective threading of the catheter in a predetermined direction withinthe epidural space.

To provide an injection instrument admitting of safe, easy insertion andplacement of a relatively large bore catheter, and to overcome theshortcomings of the prior art, a novel exteriorly disposedcatheter-needle has been invented.

SUMMARY OF THE INVENTION The present invention is best summarized as animproved instrument for administering fluids into the channels andcavities of a subject including a hollow needle, through which fluidsmay be introduced or withdrawn, the needle further including a needlehub assembly thereon; a catheter member disposed exteriorly of theneedle and slidable thereon; and a catheter hub aifixed to the proximalend of the catheter member, the catheter hub being constructed toreleasably interlock with the needle hub assembly to selectively fix theneedle in a predetermined position with the catheter member.

The novel features which are considered characteristic of the presentinvention, both as to its organization 3 and operation, will be betterunderstood from the following description considered in connection withthe accompanying drawings of an embodiment of the invention. It isexpressly understood, however that the drawings are for the purpose ofillustration only and are not intended as a definition of the limits ofthe invention. When viewed in the light of the preceding prior artdiscussion, the description and the drawings lend clear support to theadvantages of the present invention as stated immediately thereafter.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: FIGURE 1 is anoverall perspective view; FIGURE 2 is a partial section taken along thelines FIGURE 3 is a sectional view taken along the lines 33;

FIGURE 4 is a partial section taken along the lines 2-2;

FIGURE 5 is a sectional view taken along the lines 5-5;

FIGURE 6 is an alternative embodiment to FIGURE 2. in partial section;

FIGURE 7 is a partial section expanded over FIG- URE 6;

FIGURE E is a side elevation in partial section;

FIGURE 8a is an enlarged section taken at 8a;

FIGURE 9 is a side elevation in partial section;

FIGURE 9a is an enlarged section taken at 9a;

FIGURE 10 is a side elevation in section;

FIGURE 11 is a side elevation in partial section;

FIGURlE 12 is a side elevation in partial section;

FIGURE 13 is a side elevation in partial section; and,

FIGURE 14 is a side elevation in partial section.

DETAILED DESCRIPTION OF AN EMBODIMENT In thedrawings, a given referencenumeral is used to refer to the same part in all views.

Referring to FIGURES 2 and 4, there is shown a disposable hollow needle10 which defines a longitudinal bore 12 throughout its length. Any ofthe standard materials now utilized in the manufacture of disposableintravenous needles are suitable for the present invention. While thelength and gauge of the needle 10 is not critical to the presentinvention, a needle length of three to three and one-half inches hasbeen found to be satisfactory.

The needle 10 is ground, at one end thereof, to form the point andgenerally elliptical cutting edge 16. A point angle 17 of 45 has beenfound to provide an ease of introduction as well as the relatively shortcutting edge axial length desirable in epidural applications.

The catheter member, or catheter 18, is an elongated, flexible plasticmember designed to fit snugly about the needle 10 yet remain slidablethereon. At a terminal end 20 of the catheter 18, its outside diametergradually decreases to form the tapered, wedge-like introducing surface22. The inside diameter of the catheter may be uniform throughout itslength as in the embodiment shown.

The catheter 18 may be fabricated of any flexible material common to theart. For epidural administrations a catheter made of the product Teflonis preferably employed to decrease frictional drag through the bodytissue and ligaments thus facilitating introduction. Referring to FIGURE14, the catheter may also be constructed to include the substratesection 19, made of such polymeric materials as polyvinyl, polyethyleneand polypropylene; and the coating section 21 made of such polymericmaterials as exhibit self-lubricating surface characteristics like theproduct Teflon and the organopolysiloxanes. The organopolysiloxanes usedmay generally be depicted as having the generic structure where R may beCH CH =CH or other alkyl groups.

As will be shown more clearly hereinafter, the length of the catheter 18is critical to the present invention and primarily dependent on needlelength.

At a proximal end 24 of the catheter 18, the catheter hub 26 isconcentrically affixed to the catheter. The hub 26 is preferablyconstructed of a non-flexible material such as a suitable metal, alloy,or plastic. In the embodiment shown in FIGURE 2, the exteriorconfiguration of the hub 26 is substantially frusto-conical. The definedexterior surfaces of the hub include the interlocking surface 28 and themale mating surface 30. The mating surface 30 has a configuration commonto intravenous to venous connections known in the art.

The hub 26 is constructed to define therethrough the axial opening 32.The opening 32 must be of sufficient diameter to admit of the passage ofthe needle 10. The hub 26 further defines, in cooperation with theopening 32 the axial keyway 34 having an open end 36 and a bearingshoulder 38. The open end 36 and the shoulder 38 are spaced apart apredetermined axial distance. In a present embodiment of the invention,an axial separation of two to four millimeters is preferable.

The needle hub 40 is concentrically disposed at the end of the needle 10opposite the point. The hub 40 is constructed to removably receive onone side thereof, in any standard manner known in the art, a disposablesyringe 42. The hub 40 includes the axial key 44 disposed oppositely onthe hub from the syringe. The key 44 is constructed to such dimensionsas to be matable within the keyway 34; the key bearing surface 46abutting the keyway shoulder 38 when the needle hub 40 and the catheterhub 26 are in full mating relationship.

It is to be recalled that the catheter 18 has a critical lengthprimarily dependent upon needle length. The axial separation between thekeyway end 36 and shoulder 38 is also critical. The catheter length issuch that when the needle and catheter hub are in full matingengagement, substantially all of the needle is enclosed within thecatheter except the sloped surface of the point and portions of theneedle immediately adjacent therto. The axial length of the keyway 34must be such that when the needle 10 is withdrawn from the catheter 18an amount equal to that. axial length, the needle point is withdrawninto the catheter a distance sufficient tc completely cover he point andcutting edge, yet no further. Thus, necessary rigid support of the tip22 of the catheter is maintained. As indicated above, in the embodimentshown this withdrawal distance is approximately two to four millimeters.

With reference to the foregoing and FIGURES 3, 4 and 5, it may be seenthat when the needle 10 has been withdrawn the requisite distance, thebearing surface 46 of the key 44 will exit the keyway 34 leaving theneedle free to rotate. A slight rotation of the needle in eitherdirection will place the bearing surface 46 in abutment with theinterlocking surface 28 of the hub 26. The needle is thereby lockedagainst further advancement into the catheter.

It is to be understood that it is the withdrawal of the needle pointinto the catheter, and its fixed position therein, that is critical.While a simple interlocking key arrangement is shown in the embodimentpresented, the same axial withdrawal distance and interlock effect maybe achieved by other similar mechanical arrangements. Otherpossibilities include eamming surfaces; screw type assemblies; and blockwedge relationships.

Referring to FIGURES 6 and 7 there is shown an alternative embodiment ofthe present invention. This embodiment is of substantially the sameconstruction as that described above. However, the catheter hub 26' isdepicted as defining the female fitting 48 for connection with exteriortubing having a male connector. In this embodiment, the key 44 isdisplaced from the needle hub proper by an amount equal to the depth ofthe female fitting surface. The key thus disposed is supported by theextension member 52.

Referring now to FIGURES l1 and 12, there are shown illustrativealternative embodiments of the catheter 18. As shown in FIGURE 12, thecatheter 18 has been preformed to define a naturally curved portion atthe terminal end 20 of the catheter. As indicated herein before, it ispreferably constructed of a flexible plastic material. Thus, when theneedle is introduced through the catheter 18, the curved portion ismaintained in a substantially straight position. However, the plasticmemory of the preformed curved portion will cause the catheter to againresume its curved posture upon withdrawal of the needle. Correlatively,the direction mark 80 provided on the catheter hub 26 indicates to apractitioner the direction in which the curved end of the catheter willtend upon removal of the needle.

Referring to FIGURE 11 there is shown an additional alternative catheterembodiment wherein a plurality of Winged stops 82 are circumferentiallydisposed about the catheter near its terminal end 20. Each of the stops82 in an integrally performed cut-out portion of the catheter wall 84.The stops 82 are preformed to assume a normally expanded position withrespect to the catheter wall 84. Upon introduction through a surface,the stops 82 are constructed to resiliently assume a position coincidentwith the catheter wall. Following complete insertion through the surfacethe stops are free to resiliently return to their normally expandedposition thereby creating an impediment to catheter withdrawal throughthe surface of insertion. Again, however, the natural flexibility of thecatheter material may be such as to safely admit of catheter withdrawalagainst the biasing effect of the winged stops 82.

Having thus seen the physical arrangement of the parts of the presentinvention, a description of their cooperation in an illustrativeapplication follows. Referring to FIG- URES 8 and 9, a stylet of a typecommonly known in the art, but not shown, is inserted into the needle 10to prevent fouling of the needle bore 12. The needle, with itsexteriorly disposed catheter 18 in full mating relationship with theneedle, is then introduced through the subjects back tissue into theinterspinous ligaments 56. The stylet is then removed and a liquid orair loaded syringe 42 is attached to the needle. Continuous fluidpressure is maintained as the needle is urged closer to the epiduralspace 58. The density of the interspinous ligaments provides a greatresistance to the flow of liquid out of the needle. This resistancebecomes even more marked as the needle enters the denser ligamentumflavum 57. A marked decrease in the resistance to flow indicates entryof the needle point through the ligamentum flavum into the epiduralspace 58. This decreased resistance would indicate needle entry into theepidural space but not necessarily catheter entry. The self-lubricatingqualities of the catheter 18 has rendered insertion through theinterspinous ligaments relatively easy. However, because of theaforementioned precedent relationship of the needle to the catheterintroducing surface 22, as the smaller diameter needle penetrates theligamentum flavum, the wedge-like introducing surface 22 encounters thedenser ligamentum flavum thereby creating a greater penetrationresistance. See FIGURE 8a. Such increased penetration resistance,together with the decreased fluid flow resistance, indicates to thepractitioner that not only has the needle entered the epidural space butalso that the needle point and cutting edge are nearing criticalproximity to the dura. Consequently, further advancement of the needleis ceased and the needle is immediately withdrawn in the catheter to itslocked position as shown in FIGURES 9 and 9a. As previously described,the needle is withdrawn no further than is necessary to cover the point;yet the needle provides a rigid support for continued introduction ofthe catheter through the pre-dilated ligamentum flavum. After needlewithdrawal into the catheter, fluid pressure is again applied. It thecatheter is not in the epidural space, it is now rigid enough to serveas a blunt introducer Which will repierce, or dilate the remaining smallamount of ligamentum flavum. The blunt point of the catheter 18 willprevent puncture of the dura 62. After advancement of the lockedcatheter needle, a decreased resistance to fluid flow will now signifythe entry of the catheter in the epidural space. The needle may now becompletely withdrawn leaving the catheter fixed in the epidural space bythe interspinous ligaments. A portion of the catheter and the catheterhub project exteriorly of the patients skin or introducing surface.Necessary connections may now be made through the catheter foradministration of the anesthetic agent.

In some applications it has been found that, following placement of thecatheter 18, the terminal end 20 is placed in such flush proximity tothe dura 62 as to obstruct or preclude the flow of fluid through thecatheter. See FIGURE 10. Referring to FIGURE 12, it may be seen thatsuch an obstruction may be overcome by utilizing the curved-end catheterpreviously described. While the catheter remains substantially straightduring the insertion procedure described above, upon removal of theneedle the curved end of the catheter returns to its normally curvedposition within the epidural space. The direction in which the catheteris to be trained may be easily selected by the practitioner withreference to the correlative direction mark on the catheter hub 26.Alternatively, the additional catheter embodiment depicted in FIGURE 11may be employed to further fix the catheter within the epidural space aswell as provide an unobstructed fluid exit through the openings 86 inthe catheter wall 84 created by the pre-formation of the expanded wingedstops 82.

A further alternative to final catheter placement within the epiduralspace is shown at FIGURE 13. Therein, the fine, small bore catheter 88,with a pretrained tip, is threaded through the catheter 18 into theepidural space. Using the fine catheter 88 as a curved introducingguide, the practitioner may then further insert the catheter 18 into theepidural space thereby precluding the undesirable flush proximity of thecatheter terminal end 20 and the dura 62.

While the construction and use of the present invention catheter needlehas been above described in terms of an epidural administration, it mayreadily be seen by one of ordinary skill in the art, in light of theshortcomings of the known techniques, that the insertion and catheterplacement advantages thereof may be utilized in intravascular andintracavity applications as well.

There has thus been described an improved catheterneedle insuringgreater subject safety as well as case and reliability of use.

The novel withdrawable interlocking catheter-needle relationship greatlyminimizes the possibility of harmful penetration of the dura andfacilitates accurate placement of the catheter. Concurrently however,each of introduction is retained with the sharp needle point and theselflubricating characteristics of the Teflon or silicone cathetercoating. In the present invention catheter-needle, the catheter is inplace when the needle is positioned; no awkward catheter threading isrequired.

Added safety is found in the exteriorly disposed large bore catheter.All drugs are introduced through the catheter. The large bore catheterallows easy injection and reliable aspiration. The large bore catheteris much less likely to erode into either a blood vessel or thesubarachnoid space because of its location and novel mode of placement.

What is claimed is:

1. An instrument for administering an epidural anesthesia comprising:

(a) a hollow needle through which fluid may be introduced or withdrawn,said hollow needle including a needle hub assembly having interlockmeans;

(b) a catheter member made of a resilient material more flexible thansaid needle, having a smooth exterior surface and of predeterminedlength disposed exteriorally on said needle and having an internaldiameter substantially the same as the diameter of said needle wherebyit is slideable thereon, said catheter terminating at an end thereof ina catheter hub; and

(c) said catheter hub having interacting means for releasablyinterlocking with said interlock means of said needle hub assembly toselectively fix said needle in a predetermined position within saidcatheter member.

2. In the combination defined in claim 1, wherein:

(a) said catheter hub defines therewithin a recess of predeterminedaxial length terminating in an interlocking surface;

(b) said needle hub assembly defines thereon a projection slideablewithin said recess; and,

() wherein said projection is constructed to abut with said interlockingsurface and maintain said needle in said predetermined position whensaid needle is withdrawn into said catheter a distance equal to saidpredetermined axial length of said recess.

3. In the combination defined in claim 1 wherein said catheter member ismade of a resilient polymeric material having self-lubricating surfacecharacteristics.

4. In the combination defined in claim 3 wherein said polymeric materialis selected from the group consisting of polytetrafluoroethylene,fiuorinated ethylene-propylene and polyethyleneterephthalate.

5. In the combination defined in claim 3 wherein said catheter member ispreformed to define a normally curved portion at an end thereof axiallyopposite said catheter hub, said curved portion being adapted tomaintain a substantially straight position when said catheter and saidneedle are in full mating relationship.

'6. In the combination defined in claim 1 wherein said cathetercomprises a substrate section and a coating section, said coatingsection being imposed on said substrate section and havingself-lubricating surface characteristics; said substrate sectioncomprising a polymeric material selected from the group consisting ofpolyvinyl, polyethylene and polypropylene, and said coating sectioncomprising a polymeric material selected from the group consisting ofpolytetrafiuoroethylene, fluorinated ethylenepropylene,polyethyleneterephthalate and organopolysiloxanes.

7. In the combination defined in claim 1 wherein an end of said cathetermember axially opposite said catheter hub includes a plurality of wingedstops circumferentially spaced about the catheter wall, each of saidstops having a fixed end coincident with said catheter wall and abearing end outwardly pivotally expandable about said fixed end, each ofsaid stops being adapted to be positioned in a normal first positionoutwardly expanded with respect to said catheter wall and a secondposition coincident with said catheter wall.

8. The method of administering an epidural anesthesia into the spinalstructure of a subject including the steps of:

(a) introducing a hollow needle having a first catheter memberexteriorly slidable thereon into the interspinous ligaments of saidspinal structure into the epidural space of said spinal structure;

(b) withdrawing said needle into said first catheter a predetermineddistance and locking said needle within said first catheter againstfurther introductory motion with respect to said first catheter;

(c) introducing said first catheter into said epidural space;

((1) entirely withdrawing said needle from said first catheter; and,

(e) introducing an epidural anesthetic agent through said first catheterinto said epidural space.

9. The method recited in claim 8 including the additional steps of:

(a) threading a second catheter having a trained tip and a diametersmaller than that of said first catheter through said first catheterinto said epidural space;

(b) threading said first catheter into said epidural space on saidsecond catheter; and,

(c) withdrawing said second catheter.

10. A combination as defined in claim 1 and further including:

((1) a syringe receiving and retaining said hollow needle.

References Cited UNITED STATES PATENTS 1,248,492 12/ 1917 Hill l283472,862,495 12/1958 Gewecke l2822l 2,922,420 1/1960 Cheng l2822l 3,094,1226/ 1963 Gauthier et al. l2822l 3,277,893 10/1966 Clark l2822l XR3,308,819 3/1967 Arp l2822l XR 3,312,220 4/ 1967 Eisenberg l2822l XR3,419,010 12/ 1968 Williamson l28350 3,358,684 12/1967 Marshall128--214.4 3,406,685 10/ 1968 May l2822l XR 3,406,687 10/1968 Moyerl2822l FOREIGN PATENTS 605,067 2/ 1926 France.

WILLIAM E. KAMM, Primary Examiner US. Cl. X.R. 1282l4.4

